An Educated Guess - Predicting Turbomachinery Efficiencies of Aero Engines During Conceptual Design

Abstract

Evolutionary advancements and disruptive concepts for future gas turbine-based propulsion systems are researched to reduce the environmental impact of aviation. In the initial design phase, only few data on component efficiencies is available and assumptions have to be introduced. However, comparability and consistency between assumed efficiencies is crucial to benchmark different designs or concepts in a feasible way and to avoid misleading findings. The assumptions made have to reflect the impact of design parameters on efficiency considering underlying physical phenomena. A simple model is developed to predict the design efficiencies of axial flow turbo components of aero engines with the aim to generate traceable, consistent and comparable assumptions for conceptual engine design. The efficiency prediction model combines existing approaches from published sources using a superposition principle and is calibrated by means of available data on engines with an entry into service later than 2010. For a stage-wise evaluation approach, the calibrated model predicts the component efficiencies of database engines with a maximum absolute deviation of 0.1 % for fans, 2.2 % for compressors, 1.4 % for cooled turbines and 0.6 % for low-pressure turbines. The deviations between predictions and database values create a sense for the uncertainty that has to be expected using the calibrated model. The future application of the predictive capability contributes to feasible comparisons between different engine configurations during the conceptual design phase.